Temperatures are measured in many industrial and commercial systems and processes to provide desired conditions in which the systems and processes operate. By accurately measuring the temperatures of the systems and industrial processes, the associated equipment can operate at an optimum efficiency. Temperature measurements made for a combustion engine can be particularly critical, since the efficiency of the engine can be directly related to the temperature at which the engine operates.
Some applications for temperature sensing present a harsh or extreme environment which can affect the capability of a temperature sensor to accurately determine a temperature. For example, in some types of combustion engines, the temperature of the engine exhaust can provide an accurate indicator of the operating conditions of the engine. However, due to the harsh environment of the exhaust gas, the temperature sensing systems and the temperature sensors themselves, require robust packaging to prevent the extreme environment from affecting the temperature measurement. Highly complex packaging to protect the system or sensor can be required. Unfortunately, packaging of this type, while effective, can be costly or complex. In addition, additional electrical circuitry and the associated wiring may be needed to transmit the electrical temperature signals in an extreme environment. As a result, there are a relatively few number of currently available temperature sensors which can be used for such extreme applications.
Commercially available temperature sensors are known which measure temperatures at predetermined discrete periods of time, typically on the order of every few seconds or more. Such discrete measurement time periods can be too long for certain types of applications, and are therefore not suitable for fast, cycle-by-cycle temperature measurements. In particular, discrete time measurements, on the order of every few seconds, are not useful for control of advanced combustion strategies such as Homogeneous Charge Compression Ignition (HCCI) and Spark Assisted Compression Ignition (SACI) used in combustion engines.
Therefore, there is a need for a fast temperature sensor that is usable in harsh or extreme environments without requiring complex packaging.